Heat regenerative deodorizing filter

ABSTRACT

A thermally regenerative deodorizing filter, which comprises a deodorizing filter comprising a deodorant which is adaptable to a thermal regeneration and a honeycomb base material having a heat conductivity which carries the deodorant, and a heating element for regenerating the deodorizing filter which is integrated in the deodorizing filter, wherein the heating element is controlled to a predetermined temperature during the regeneration.

TECHNICAL FIELD

The present invention relates to a thermally regenerative deodorizingfilter which can be repeatedly used by heating. More specifically, thepresent invention relates to a thermally regenerative deodorizing filterintegrated with a heating element, which is able to exhibit an aimedcatalytic activity efficiently by using a temperature controllable PTCheater as the heating element to be used.

BACKGROUND ART

Hitherto, offensive smells industrially emitted in factories and thelike and offensive smells derived from wastes in service industries suchas restaurants and hotels have been considered to be problematic.Recently, bad smells in spaces of daily life such as in automobiles andin common rooms have come under closer scrutiny.

Therefore, there are increasing needs for removal of harmful substancessuch as these smells, and hence air cleaners integrated with adeodorizing apparatus or a deodorizing filter have been activelydeveloped.

On the other hand, in consideration of the global environment, reductionin weight of wastes is desired and it becomes a problem that thedeodorizing filter turns into waste after use. Thus, it is required touse the deodorant filter repeatedly by regeneration.

Some of recent home electric appliances such as air conditioners haveadopted a mode of regenerating their deodorizing ability by cleaning afilter with water or a detergent after using (for example, seeJP-2002-066223 and JP-2001-070418). However, it is necessary for a userto remove and wash the filter regularly, and therefore, a moreconvenient regeneration method is desired.

In recent air cleaners, filters containing active carbon are employedand a method of removing harmful substances such as offensive smells byadsorbing thereof on the active carbon is adopted.

Among all, a deodorizing filter in which particulate active carbon ispacked into cells of a honeycomb and both openings of the honeycomb aresealed with a gas-permeable base material has a large amount of activecarbon per a unit volume and exhibits a high gas-permeability taking theamount of active carbon into consideration. Thus, it is especiallyexcellent as a deodorizing filter using active carbon and hence isemployed in various air cleaners.

Among recent air cleaning equipments, an equipment mounted with adeodorizing filter which is packed with active carbon capable ofregeneration by washing with water has been commercially available, butthe washing operation is difficult. Further, in general, the washingwith water can regenerate the filter when hot water is used, butcomplete regeneration effect cannot be obtained when low-temperaturewater like tap water is used. In addition, since the particulate activecarbon is not easily dried after washing, more convenient and effectiveregeneration method is desired.

Recently, there has been a raw garbage disposer in which a plate-formheater is provided in close contact with a honeycomb surface of acatalyst to impart a mechanism of thermal regeneration at 200° C. to300° C. when the catalyst reaches saturation for adsorption of odors andoxidative decomposition and its deodorizing ability decreases.

However, in general air conditioning equipments, continuous use isproblematic since it is a rare case where a heat source capable ofachieving such a high temperature of 200° C. or higher is available and,in the case of using a catalyst, regeneration efficiency by thermaltreatment is remarkably lowered when the catalyst surface is coveredwith dirt, dust, and the like and hence the catalyst becomes physicallyimpossible to work (cf. JP-A-7-136628).

As the other equipment, there is reported a deodorizing equipment inwhich regeneration of deodorization performance is intended by heatingan absorbent through electrification of the adsorbent as a heating meansof odor components. However, the deodorant should be anelectroconductive substance or a material having no conductivity shouldbe subjected to a treatment for suitable impartment of conductivity. Inaddition, even when the adsorbent is electrified, it is virtuallydifficult to achieve uniform electrification of all over the adsorbentof the whole filter to reach a constant elevated temperature, so thatthe equipment is not suitable for practical use (cf. JP-B-7-16579).

Furthermore, as a deodorizing filter for an air cleaner, there is knowna filter in which a deodorizing filter made of a non-woven fabric formedwith a carbon fiber and capable of effecting deodorization by thereaction of the carbon fiber with odor components in the air and ofreleasing the adsorbed odor components by heating at about 110° C. isshaped into a flat pouch and a plate-form heater having air permeabilityis enveloped in the pouch-like deodorizing filter to integrated them,but the filter has a problem in view of regeneration efficiency (cf.JP-A-10-332).

An object (purpose) of the invention relates to a deodorizing filterhaving a large capacity of deodorization performance and is to provide athermally regenerative deodorizing filter which can be repeatedly usedby conducting a thermal regeneration treatment.

SUMMARY OF THE INVENTION

The summary of at least one embodiment of the invention solving theabove problems lies on the following.

A thermally regenerative deodorizing filter comprising:

a honeycomb base material of a deodorizing filter, which comprises atleast a first kind of electroconductive sheet and a second kind ofelectroconductive sheet,

a deodorant packed in a cell of the honeycomb base material, and

a gas-permeable base material sealing openings at the both sides of thehoneycomb base material,

wherein at least-one of said kinds of electroconductive sheets comprisesa PTC heater and at least one of said kinds of electroconductive sheetsdoes not comprise a PTC heater.

A thermally regenerative deodorizing filter, which comprises a honeycombbase material, a deodorant packed in a cell of the honeycomb basematerial, and a gas-permeable base material which seals openings at theboth sides of the honeycomb base material,

wherein the honeycomb base material comprises a PTC heater,

the gas-permeable base material comprises an electroconductive material,and

the PTC heater is heated by applying a voltage between the gas-permeablebase material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a drawing showing an example of a combination of a deodorizingfilter and a heating element which are constituents of the thermallyregenerative deodorizing filter of at least one embodiment of theinvention.

FIG. 2 is a drawing showing an example of a combination of a deodorizingfilter and a heating heater which are constituents of the thermallyregenerative deodorizing filter of at least one embodiment of theinvention.

FIG. 3 is a drawing showing an example of a combination of a deodorizingfilter and a heating element which are constitutive elements of thethermally regenerative deodorizing filter of at least one embodiment ofthe invention.

FIG. 4 is a drawing showing a whole constitution of the thermallyregenerative deodorizing filter of at least one embodiment of theinvention.

FIG. 5 is a drawing showing an example of an arrangement of anelectroconductive sheet and a sheet-form PTC heater which are corrugatedconstituents of at least one embodiment of the invention.

FIG. 6 is a drawing showing an example of an arrangement of anelectroconductive sheet and a sheet-form PTC heater which are corrugatedconstituents of at least one embodiment of the invention.

FIG. 7 is a drawing showing a whole constitution of the thermallyregenerative deodorizing filter of at least one embodiment of theinvention.

FIG. 8 is a drawing showing a low-temperature state of an organic PTCheater.

FIG. 9 is a drawing showing a high-temperature state of an organic PTCheater.

In FIGS. 1 to 9, 1 is a heating element, 2 is a deodorizing filter, 3 isa deodorant, 4 is a gas-permeable base material, 5 is anelectroconductive sheet, 6 is a sheet-form PTC heater, each of 7 and 8is a voltage applying part, 9 is a PTC heater, 10 is a gas-permeablebase material, 11 is a deodorant, 12 is a crystalline macromolecularpolymer, 13 is an electroconductive fine particle, and 14 is a tabularelectrode.

DETAILED DESCRIPTION OF THE INVENTION

The following will explain a first embodiment of the thermallyregenerative deodorizing filter of the invention in detail.

Since the thermally regenerative deodorizing filter of at least oneembodiment of the present invention is deodorized and regeneratedefficiently by heating, it is specific that the part containing adeodorant has a honeycomb constitution. The constituents constitutingthe honeycomb base material, such as a thermally conductive material anda deodorant, preferably have heat resistance.

The honeycomb base material to be used in at least one embodiment of theinvention is a structure comprising cell walls having openings, and aspecific example of the honeycomb base material is a corrugatedhoneycomb obtainable by laminating single faced corrugated fiberboardmanufactured in accordance with “exterior corrugated fiberboard”described in JIS-Z-16-1995, the honeycomb being described inJP-A-3-67644 or JP-A-5-338065.

A hexagon honeycomb composed of hexagonal cells, a honeycomb composed ofsquare cells, a honeycomb composed of triangular cells, a honeycombcomposed of hollow cylindrical cells, and the like, which aremanufactured by the method may be mentioned.

The cell shape such as hexagon or square may be not only a regularpolygon but also an irregular one with the rounded angle or the curvedside.

The honeycomb base material according to the least one embodiment of theinvention preferably possesses heat resistance and a honeycomb basematerial made of various thermally conductive materials having heatresistance, which is shaped by an adhesive having heat resistance to bementioned below, can be employed.

The deodorant which is adaptable to thermal regeneration according to atleast one embodiment of the invention is preferably a porous deodorantwhich is easy to regenerate by heating and should have heat resistanceagainst the temperature of the heating element (PTC heater).

The material which can be used as the deodorant adaptable to the thermalregeneration according to at least one embodiment of the invention arethe materials which are employed mainly for the purpose of removingoffensive odors. Specifically, there may be used carbon-based adsorbingdeodorant such as active carbon; for the purpose of strengtheningdeodorization performance against specific odor components, for example,active carbon impregnated with an amine-based substance fordeodorization of aldehyde or a chemical agent such as an organic acidfor deodorization of ammonia, active carbon fiber, bamboo charcoal andBincho charcoal; an inorganic absorbing deodorant such as natural orsynthetic zeolite (zeolite group), active alumina, an iron-basedcompound such as iron oxide, and porous silica; enzyme-based deodorantsuch as iron ascorbate or a phthalocyanine derivative of a metal such asiron, cobalt, or manganese; an oxidation catalyst such as amanganese-based oxide, a perovskite compound, platinum oxide, palladiumoxide, or vanadium oxide; a composite of silicon carbide, siliconnitride, calcium silicate, aluminum oxide and silica; synthetic ceramicsuch as zirconia and far infrared ray ceramics such as heals stone orfergusonite, as well as, in the case that a temperature range of usingthe heating element is relatively low temperature, an organic adsorbingdeodorant such as an organic acid-based compound, chitin, chitosan, andan ion exchange resin; a deodorant using a compound contained in a plantextract, such as catechin, tannin, flavonoid, limonen, or pineneplurality of these deodorants may be optionally used in combination ormay be used as a hybrid deodorant by complexing these deodorants.

As the deodorant, particularly preferred is high-silica zeolite.Although, similar to usual zeolite, high-silica zeolite (hydrophobiczeolite) is a crystal of an aluminasilicate metal salt, the ratio ofsilica to alumina in the crystal is particularly high. Since the oxygenatom in the silica structure hardly has basicity and the Si—O—Si bond onthe surface does not participate in the formation of hydrogen bonding,high-silica zeolite shows hydrophobicity and does not adsorb watermolecules and hence it can effectively adsorb aldehydes and the likeeven under a highly humid environment and under a high temperatureenvironment.

Furthermore, high-silica zeolite has a feature that it can adsorb a widerange of odorants including low-temperature compounds such as aldehydeswhich are generally difficult to remove by an adsorption method, forexample, organic acids, ammonia, amines, ketones, sulfur-containingcompounds such as hydrogen sulfide and mercaptans, indols and the like.

In addition, since it is excellent in adsorption of hydrophobic gasesand neutral gases which are difficult to remove by regeneration withwater washing, it is possible to complement the deodorizationperformance of a particulate deodorant which is suitable forregeneration with water washing, and thus the total deodorization can beachieved.

The honeycomb base material to be used in at least one embodiment of theinvention is preferably any of alumina, silica, magnesium oxide, calciumoxide, nickel oxide, zinc oxide, titanium oxide, iron oxide, siliconcarbide, titanium carbide, tantalum carbide, silicon nitride, aluminumnitride, boron nitride, beryllium oxide, silver, copper, aluminum,nickel, glass, graphite or a mixture thereof, as a material having ahigh thermal conductivity. The aforementioned oxides, carbides, andnitrides all have a heat conductivity of 10 W/m·k or more, and hence aresuitable. Among them, particularly alumina, silica, zinc oxide, andsilicon carbide are inexpensive and preferable.

These heat conductive materials may be used as an electroconductivesheet using a binder or may be supported on by surface treatment or thelike of a sheet.

By using a heat conductive material, it becomes possible to transferheat of the PTC sheet to the whole honeycomb effectively, and it resultsin improvement in thermal regeneration efficiency of the filter.

Although the heating element to be brought into contact with the heatconductive material in at least one embodiment of the invention is notnecessarily subjected to insulation treatment, it is preferred foreither the heat conductive base material or the heating element to havean insulating property.

In the case that the insulation treatment is performed, it is possibleto use a material comprising an inorganic oxide, carbide, nitride, orthe like or a material subjected to surface coating with aheat-resistant resin. As the surface coating agent, it is preferred touse a material which does not deactivate the performance of thedeodorant to be supported.

As a method of supporting the deodorant on the honeycomb base material,the most convenient method may be a method of preparing a coating liquidin which the deodorant and a binder is dispersed after the formation ofthe honeycomb and then supporting it on the honeycomb surface byimpregnation.

In addition, the supporting may be performed by a method of coating at astage of sheet-form prior to processing into the honeycomb.

In this connection, since the binder to be used may cause deteriorationof deodorization performance depending on the ratio thereof, it ispreferred to restrict the ratio to not more than 60% of the totalsupporting weight.

The material of the heating element in at least one embodiment of theinvention preferably comprises a heating body composed of either aceramic heater or a linear heater made of tantalum, nichrome, ortungsten; or the heating body and a heat conductor.

As the heating element in at least one embodiment of the invention,there may be mentioned a heating body composed of either a ceramicheater or a linear heater made of tantalum, nichrome, or tungsten; orone having an electromicrowave generator, such as a microwave.

Among all, in view of easiness of ON/OFF switching and temperaturecontrol and simplicity of the structure, a heating body composed of apanel heater which tightly holds a linear heater composed of nichromewhose surface is subjected to insulation treatment, between two aluminumplates is preferred. There may be suitable a heating body in which heatof a heating heater selected from them is efficiently transferred to thedeodorizing filter through the heat conductive material to effectheating.

With regard to the combining method of the heating element with thedeodorizing filter, as an example of attachment is shown in FIG. 1,there is adopted a form wherein the heating element is tightly adheredto the honeycomb base material in a form of shaping an outer flame whichis parallel to the deodorizing filter having a hollow tubular structure.

Specifically, the element is placed in a form of tightly adhered to aliner of the outer flame of the honeycomb base material or so as to comeinto contact with the inner core of the corrugate while playing a roleof liner. Any manner may be suitable as far as heat of the heatingelement (heating heater) 1 is transferred to the deodorizing filter 2 byadopting this structure.

The heating element and the deodorizing filter is needed to be come intocontact with each other at least one part. It is preferable to attachthe heater to a plurality of sides at the circumference of thedeodorizing filter as shown in FIG. 2, or to cover all the circumferenceof the deodorizing filter as shown in FIG. 3.

When an adhesive is used for the attachment of the heating element tothe deodorizing filter, a heat-resistant adhesive which is sustainableto the temperature reachable by the heating element can be suitablyselected and used. However, when the opening of the honeycomb is closed,a sufficient airflow is limited thereby, so that it is preferred toattach the heating element so as not to close the opening as far aspossible.

As a heat-resistant adhesive to be preferably used, an ethylene-vinylacetate copolymer, a polyamide, a polyester, or a synthetic rubber-basedhot-melt adhesive is employed and, furthermore, there may be mentioned astyrene-butadiene-styrene triblock copolymer, a pre-condensate composedof N,N′-(4,4′-diphenylmethane)bismaleimide and4,4′-diaminodiphenylmethane, a coumarone-indene resin and a terpeneresin, an adhesive obtained by further blending a terpene-phenol resinthereto, or the like, but the heat-resistant adhesive is notparticularly limited thereto as far as it is used in a state sustainableto heat of the heating heater.

Next, the following will describe a thermally regenerative deodorizingfilter of a second embodiment of the invention in detail.

The thermally regenerative deodorizing filter is a thermallyregenerative deodorizing filter aiming at efficient thermal regenerationby particularly using a temperature-controllable PTC heater as theheating element, and the constituents such as the heat-conductive basematerial, the deodorant, and the adhesive to be used for the thermallyregenerative deodorizing filter preferably have heat resistance.

PTC to be used for the heating element in the thermally regenerativedeodorizing filter in at least one embodiment of the invention is anabbreviated designation of standard nomenclature “Positive TemperatureCoefficient”, and a ceramic PTC heater comprising barium titanate(BaTiO3) or vanadium oxide (V₂O₃) as a main component, or an organic PTCheater obtained by dispersing conductive particles of carbon black, ametal, or the like can be employed.

The ceramic PTC heater evolves heat when an electric current flowsthrough the element at electrification, whereby the temperature elevatesto Curie temperature. The PTC heater has a function that the ohmic valueincreases at around Curie temperature to reduce the electric current.

When the electric current is reduced, the temperature of the PTC isgradually lowered and then the electric current again flows to evolveheat. Thus, the PTC heater has a property that the temperature thereofis controlled at around set Curie temperature.

Moreover, the organic PTC heater is a heater in which a tabularelectrode 14 is provided on the surface of a PTC heater element having ashaped constitution in which electroconductive particles 13 of carbonblack, a metal, or the like are dispersed into a crystalline polymer 12,as shown in FIG. 8. Under a low-temperature condition, a myriad ofelectroconductive paths are present between respective electrodes andthe resistance is low.

On this occasion, when a voltage is applied to the electrodes, anelectric current flows and heat is evolved.

When the temperature reaches a temperature inherent to the material (inthe present application, this temperature is expressed as a temperaturecorresponding to Curie temperature in the case of the ceramic one), asshown in FIG. 9, a dispersed state of the electroconductive particlesbecomes uneven by the thermal expansion of the crystalline polymer, andthe electroconductive paths are broken to result in an increase of anohmic value. Thus, electric current control and simultaneous temperaturecontrol become possible.

The inherent temperature can be freely set by changing the combinationratio of the crystalline polymer to the electroconductive particles.

In comparison with the ceramic PTC heater, the organic PTC heater has alow specific resistance at room temperature and hence is suitable foruses in which a large electric current is applied. Further,miniaturization is possible and the heater also possesses aself-controlling heater and temperature-detecting andovercurrent-protecting functions, so that it can be advantageouslyemployed.

Examples of the polymer usable for the organic PTC heater includepolyethylene, polyethylene oxide, t-4-polybutadiene, polyethyleneacrylate, ethylne-ethyl acrylate copolymers, ethylene-acrylic acidcopolymers, polyesters, polyamides, polyethers, polycaprolactam,fluorinated ethylene-propylene copolymer, chlorinated polyethylene,chlorosulfonated ethylene, ethylene-vinyl acetate copolymers,polypropylene, polystyrene, styrene-acrylonitrile copolymers, polyvinylchloride, polycarbonate, polyacetal, polyalkylene oxide, polyphenyleneoxide, polysulfone, fluorinated resins, and the like. At least one ofthese polymers may be used Specifically, they are suitably selecteddepending on the method of electrode formation, required properties ofthe PTC heater, and the like.

As preferred examples of the polymer, there may be mentionedpolyethylene, Nylon 12, or polyethylene oxide PEO). Among these, when arelatively low Curie temperature of about 60 to 70° C. is targeted,polyethylene oxide or a mixture of high-density polyethylene andlow-density polyethylene with a wax is preferred. In particular, for thepurpose of lowering Curie temperature, preferred is a mixture of mixedpolyethylene with a wax or polyethylene oxide.

As the electroconductive particles for use in the organic PTC heater,there may be mentioned Ni, Ti, Cu, Ag, Pd, Au, PT, and the like as metalparticles, and particles of carbon black, Al2O3, TiO2, etc., with an Agplating layer formed thereon; particles of BaTiO3 etc., with a Pdplating layer formed thereon; and the like as metal coating particles.

The organic PTC heater using carbon black as an electroconductive fillerhas been used as a overcurrent protecting element in large quantities.It is possible to lower the resistance of an organic PTC heater usingatypical metal particles as the filler, which is currently actuallyused, to 1 mK2 or less (JP-A-5-47503).

The PTC heater using atypical metal particles as the filler is specificthat it has an extremely small ohmic value and exhibits a largeresistance-changing rate of 6 orders or more at a working temperature of80° C. When the material having a large resistance-changing rate isused, it is possible to diminish the controllable width of temperatureof the PTC element and highly accurate temperature control can berealized, so that high reliability is expected also from the practicalviewpoint.

The Curie temperature of the PTC heater can be freely designed accordingto applications, and the Curie temperature of the PTC heater for use inat least one embodiment of the invention is preferably from 60 to 180°C.

This is because, although the deodorant for use in the thermallyregenerative deodorizing filter is preferably porous zeolite or activecarbon, for complete regeneration of these materials, a temperature ofabout 100° C. to 0° C. is sufficient and air-cleaning equipments arefrequently controlled at a practical temperature of 100° C. or lowersince they cannot mount a heat source reaching a high temperature of100° C. or higher in many cases.

When the equipment is controlled at a temperature of 100° C. or lower,the regeneration rate sometimes do not reach 100%. However, the recoveryof deodorization performance of 50% or more can be expected in manycases, when a temperature of about 60° C. is applied as the heatingtemperature.

The deodorant to be used in the thermally regenerative deodorizingfilter of at least one embodiment of the invention preferably has aproperty of being regenerated at the heating temperature of the PTCheater used in at least one embodiment of the invention.

In the deodorant, although it is preferred to use a deodorant having theregenerating temperature close to the Curie temperature of the PTCheater, a PTC heater having Curie temperature lower than theregenerating temperature may be attached according to the designedprinciple of the deodorant.

Preferably, active carbon, high-silica zeolite, and the like can berecovered to initial deodorization performance by subjecting them toabout 1 hour of heat treatment at 120° C.

The PTC heater to be used in the thermally regenerative deodorizingfilter of at least one embodiment of the invention is attached so thatheat of the heater can be efficiently transferred to the filter, and theposition and the shape of the PTC heater are not limited as far as thewhole deodorizing filter is heated through a heat conductive material.

Moreover, the following will describe a thermally regenerativedeodorizing filter of a third embodiment of the invention.

Since the thermally regenerative deodorizing filter is regenerated by aPTC heater which is a heating element, the constituents such as the PTCsheet, the electroconductive sheet, the deodorant, and the adhesiveconstituting the thermally regenerative deodorizing filter preferablyhave heat resistance.

The honeycomb structural body to be used in the thermally regenerativedeodorizing filter in this embodiment may be produced, for example, bylaminating sequentially a single faced corrugated fiberboard in whichinner core is bonded onto a liner to thereby manufacture a corrugatedblock and by cutting the corrugated block perpendicular to the linersurface thereof or at a certain angle obliquely to form a deodorizingfilter of a corrugated honeycomb.

Moreover, with regard to a honeycomb filter having a square or hexagonalshape during the extension, a honeycomb filter is obtained bymanufacturing a honeycomb block with steps of pasting to a constitutingsheet in a plurality of lines at constant intervals, overlaying anotherconstituting sheet thereon, pasting thereto in a plurality of lines atconstant intervals with shifting the pitch, and further overlaying theother constituting sheet; cutting the block perpendicular to the pasteline or with maintaining at a certain angle, and finally extending thecut block.

Namely, the thermally regenerative deodorizing filter of the thirdembodiment is constituted by packing a deodorant in the cells of ahoneycomb base material and sealing both openings of the honeycomb basematerial with a gas-permeable base material, wherein the honeycomb basematerial comprises two or more electroconductive sheets and at least oneof the electroconductive sheets is a self-temperature controlling PTCheater at electrification, and the other is composed of otherelectroconductive sheet(s). When the honeycomb base material iscorrugated, it has a constitution of either a combination of anelectroconductive sheet as the inner core part and a PTC sheet as theliner part or a combination of a PTC sheet as the inner core part, andan electroconductive sheet as the liner part, and thus becomes astructure in which PTC sheets are present between electroconductivesheets.

By applying a voltage to the both ends of the structure to send anelectric current, the PTC sheet can be heated to Curie temperature.

Moreover, it may be constituted in a state in which both surfaces of thesheet-form PTC sheet are held between electroconductive electrodesheets, respectively. By sending an electric current to the electrodesheet, the electric current flows in the thickness direction of the PTCsheet, and hence the PTC sheet is evenly heated within a short period oftime.

Furthermore, in order to heat the PTC sheet efficiently, theelectroconductive base materials positioned at both sides of the PTCsheet should be independent from each other. When the base materials areshort-circuited each other, the electric current does not flow through aPTC heater part having a high electric resistance and hence the heaterdoes not evolve heat.

Therefore, when a gas-permeable sheet for sealing particulate activecarbon is attached to the opening of the honeycomb base material, it isnecessary to design the filter so as to achieve an electricallyinsulated state.

The PTC heater and the electroconductive sheet constituting thehoneycomb base material of at least one embodiment of the inventionpreferably possess heat resistance, and there can be used a honeycombbase material which is shaped by using an adhesive having heatresistance to be mentioned below.

The electroconductive sheet to be used in the honeycomb base material ofat least one embodiment of the invention is copper, aluminum, lead,nickel, chromium, titanium, gold, platinum, an iron oxide, graphite, orthe like, and aluminum is particularly preferred.

In the case of using a metal sheet, a sheet having a thickness of 50 to500 μm is used. These electroconductive sheets may be used withsupporting a deodorant, a catalyst, or the like thereon, whereby thedeodorization performance is further improved.

The electroconductive sheet to be used in at least one embodiment of theinvention preferably has heat conductivity at the same time, and theheat conductive material is preferably any of alumina, silica, magnesiumoxide, calcium oxide, nickel oxide, zinc oxide, titanium oxide, ironoxide, silicon carbide, titanium carbide, tantalum carbide, siliconnitride, aluminum nitride, boron nitride, beryllium oxide, silver,copper, aluminum, nickel, glass, and graphite or a mixture thereof. Theaforementioned oxides, carbides, and nitrides all have a heatconductivity of 10 W/m·K or more and hence are suitable. Among all,particularly alumina, silica, zinc oxide, and silicon carbide areinexpensive and preferable.

These heat conductive materials may be used as an electroconductivesheet using a binder or may be supported on by surface treatment or thelike of a sheet.

By using a heat conductive material, it becomes possible to transferheat of the PTC sheet to the whole honeycomb effectively, and it resultsin improvement in thermal regeneration efficiency of the filter.

The particulate deodorant according to at least one embodiment of theinvention is a particulate deodorant and the size of the particle may belarge enough so as not to fall out of the mesh of the gas-permeable basematerial used for sealing and also storable in the cells of thehoneycomb.

The shape of the particulate deodorant according to at least oneembodiment of the invention is not particularly limited and may bespherical, tetrahedral, hexahedral, octahedral, cylindrical,polygonal-columnar shape, rod-like, plate-like one, or the like.

Among these, a hollow columnar or tubular shape, or a concave polygonalcolumnar shape such as a star shape or a gear shape, or the like shapeis advantageous for deodorization since the surface area of theparticulate deodorant increases, and is also advantageous for gaspermeation since flow path of air can be secured in the cells of thehoneycomb base material.

As a method for manufacturing the particulate deodorant according to atleast one embodiment of the invention, there may be mentioned a methodof shaping a powdery deodorant into particles using any of variousgranulators such as an extrusion granulator, a stirring granulator, afluidizing granulator, a rolling granulator, a compression granulator,or a tableting machine, and a method of crushing a clumpy deodorant intoparticles using any of dry or wet crushing machines such as a ball mill,a vibration mill, a roll mill, a centrifugal mill, or a jet mill. Theresulting particulate deodorant can be regulated to a desired particlesize using any of various classification methods such as sieving typeand cyclone type.

The deodorant according to at least one embodiment of the inventionpreferably has heat resistance against Curie temperature of the PTCsheet and is preferably capable of regenerating the deodorizing power ofthe thermally regenerative deodorizing filter by the heat of the PTCsheet.

The material usable as such a deodorant is a material which is employedmainly for the purpose of removing offensive smells. Specifically, theremay be mentioned a carbon-based adsorbing deodorant such as activecarbon, impregnated active carbon, active carbon fiber, bamboo charcoal,and Bincho charcoal; an inorganic absorbing deodorant such as naturaland synthetic zeolite (zeolite group), active alumina, an iron-basedcompound such as iron oxide, and porous silica; an organic adsorbingdeodorant such as an organic acid-based compound, chitin, chitosan, oran ion exchange resin; an enzyme-based deodorant such as iron ascorbateand a phthalocyanine derivative of a metal such as iron, cobalt, ormanganese; an oxidation catalyst such as a manganese-based oxide, aperovskite compound, platinum oxide, palladium oxide, or vanadium oxide;silicon carbide; silicon nitride; calcium silicate; alumina-silica; asynthetic ceramic such as zirconia or a far infrared ray ceramic such asheals stone or fergusonite; or a deodorant using a compound contained ina plant extract, such as catechin, tannin, flavonoid, limonen, orpinene.

A plurality of these deodorants may be optionally used in combination,if necessary, or may be used as a hybrid deodorant by complexing thesedeodorants.

At that occasion, it is preferred to use the deodorant after granulationwith a heat-resistant binder.

The sealing of the particulate deodorant according to at least oneembodiment of the invention is performed by holding both openings of thehoneycomb, in which the particulate deodorant is packed, between twosheets of a gas-permeable base material, and the main purpose of thesealing is the prevention of falling of the particulate deodorant.

As the specific methods of sealing, a method of adhering thegas-permeable material to the end of the cell wall of the honeycomb basematerial, a method of fixing the honeycomb base material and thegas-permeable material in the process of attaching the frame, and thelike may be mentioned.

As the gas-permeable base material, in addition to woven fabrics, dryunwoven fabrics, melt-blown nonwoven fabrics, spun-bond nonwovenfabrics, air-laid pulp, wet nonwoven fabrics, various papers, nets,honeycombs, foams, sponges, felts, and the like, there may be mentionedsheets having a large number of holes made in general-purpose resinfilms and thin plates such as polyethylene film, polypropylene film, andpolyester films, as well as metal nets and the like.

In the case of using a metal net, however, it must be arranged so thatit is electrically insulated from the honeycomb part.

The gas-permeable base material according to at least one embodiment ofthe invention may possess functions of deodorization, dust removal,antibacterial ability, insect proofing ability, insect repellency, andthe like unless it deviates the gist of the at least one embodiment ofthe invention.

As the arranging method of the PTC heater to the deodorizing filter, anelectroconductive sheet (5) is arranged at the inner core part and asheet-form PTC heater (6) at the liner part regularly as in FIG. 5 or asheet-form PTC heater (6) is arranged at the inner core part and anelectroconductive sheet (5) at the liner part regularly as in FIG. 6, asshown in the explanatory drawing in detail, and they must have aconstitution capable of applying a voltage so that an electric currentflows one liner to the other of the liner parts (7, 8) at the both ends.

In particular, as shown in FIG. 5, when the sheet-form PTC heater isplaced at the liner part, since the voltage-applying terminal and thePTC come into direct contact with each other, it is preferable to use anelectroconductive sheet as the liner parts (7, 8).

When an adhesive is used in the arrangement of the PTC heater, aheat-resistant binder sustainable to the maximum temperature of theheating element can be suitably selected and used.

Moreover, the following will describe a heat regenerative deodorantfilter of a fourth embodiment of the invention in detail.

The constitution of the heat regenerative deodorant filter of at leastone embodiment of the invention is shown in FIG. 7. The heatregenerative deodorant filter of at least one embodiment of theinvention has a structure in which a particulate deodorant 11 is packedin cells of a honeycomb base material containing a PTC heater 9 and bothopenings of the honeycomb base material are sealed with a gas-permeablebase material 10 having electroconductivity so that the particulatedeodorant is not scattered and lost. Then, by electrification from thegas-permeable base material 10 at the both openings, the PTC heaterevolves heat and the sealed particulate deodorant 11 is regenerated bythe heat.

In that case, the constitutive materials of the honeycomb base materialother than the PTC should be insulators. This is because the PTC is notelectrified to be heated, when an electroconductive material is used asan element other than the PTC.

Therefore, the PTC heater, the gas-permeable base material possessingelectroconductivity, the deodorant, and the adhesive used according tonecessity, which constitute the heat regenerative deodorant filterpreferably have heat resistance against Curie temperature of the PTCheater.

Namely, the heat regenerative deodorant filter of at least oneembodiment of the invention has characteristics that the honeycomb basematerial is constituted including part of the PTC heater, the PTC heateris electrically connected with the electroconductive gas-permeable basematerial to be used for sealing the deodorant inside the honeycomb, andthe deodorization performance of the sealed deodorant is regenerated byapplying a voltage to the gas-permeable base material to heat thehoneycomb base material.

When a material other than the PTC is used as a constitutive material ofthe honeycomb base material, an insulating material is used.

The gas-permeable base material to be used for the sealing and thehoneycomb base material are preferably combined with each other in atightly adhered state, and more preferably, a large number of contactpoints are present between the gas-permeable base material and thehoneycomb base material.

This is because the presence of a large number of the contact points canresult in increasing heating efficiency. In the case of a small numberof the contact points, the electric current may flow only through pathshaving a low ohmic value, so that it takes longer time and largerelectricity to heat the whole honeycomb base material.

Moreover, the gas-permeable base materials provided at both sides of thehoneycomb base material are placed independently from each other throughthe honeycomb base material. When both gas-permeable base materials comeinto contact with each other and short-circuited, a path having a lowelectric resistance which does not pass through the PTC heater is formedand the PTC heater does not evolve heat, so that the case is, as amatter of course, not preferred.

The PTC heater constituting the honeycomb base material according to atleast one embodiment of the invention preferably possesses heatresistance and an adhesive having heat resistance to be mentioned belowcan be used for shaping a honeycomb base material and also for adheringthe gas-permeable base material possessing electroconductivity and thehoneycomb.

PREPARATION EXAMPLE 1

A hexagonal honeycomb having a cell size of 10 mm and an outside size of100 mm×200 mm×10 mm was prepared using an aluminum sheet possessing heatconductivity. This honeycomb was immersed into a coating liquid in which80% by weight of high-silica zeolite and 20% by weight of anethylene-vinyl acetate binder possessing heat resistance were dispersedso that the total concentration of solid matter was 30% by weight,whereby a deodorizing filter of Preparation Example 1 was formed. Thehigh-silica zeolite was supported in a weight of 10 g on the deodorizingfilter of Preparation Example 1.

PREPARATION EXAMPLE 2

A corrugated honeycomb having a pitch of 10 mm, a step height of 9 mm,and an outside size of 100 mm×200 mm 20×10 mm was prepared using analuminum sheet possessing heat conductivity. This honeycomb was immersedinto a coating liquid in which 80% by weight of coconut husk activecarbon and 20% by weight of an ethylene-vinyl acetate binder possessingheat resistance were dispersed so that the total concentration of solidmatter was 30% by weight, whereby a deodorizing filter of PreparationExample 2 was formed.

The high-silica zeolite was supported in a weight of 10 g on thedeodorizing filter of Preparation Example 2.

PREPARATION EXAMPLE 3

A deodorizing filter of Preparative Example 3 was formed in the samemanner as in Preparation Example 1 except that a nonwoven sheet having abasic weight of 100 g/m² and low heat conductivity, which comprises apolyester fiber and an acrylic fiber as main fibers, is used instead ofthe aluminum sheet possessing heat conductivity of Preparation Example1.

PREPARATION EXAMPLE 4

A deodorizing filter of Preparative Example 4 was formed in the samemanner as in Preparation Example 2 except that a nonwoven sheet having abasic weight of 100 g/m² and low heat conductivity, which comprises apolyester fiber and an acrylic fiber as main fibers, is used instead ofthe aluminum sheet possessing heat conductivity of Preparation Example2.

PREPARATION EXAMPLE 5

A corrugate comprising an aluminum sheet having a thickness of 0.2 mm asan inner core part and a PTC sheet having a thickness of 0.2 mm andCurie temperature of 100° C. as a liner part was prepared with a size of200 mm×100 mm×10 mm, a pitch of 10 mm, and a height of 8.5 mm, thecorrugate being a honeycomb base material of Preparation Example 5.

PREPARATION EXAMPLE 6

A corrugate comprising an aluminum sheet having a thickness of 0.2 mm asa liner part and a PTC sheet having a thickness of 0.2 mm and Curietemperature of 100° C. as an inner core part was prepared with a size of200 mm×100 mm 10×10 mm, a pitch of 10 mm, and a height of 8.5 mm, thecorrugate being a honeycomb base material of Preparation Example 6.

PREPARATION EXAMPLE 7

A honeycomb having a pitch of 12 mm, a height of 10 mm, a size of 200mm×100 mm×10 mm was prepared using a sheet-form PTC heater having athickness of 0.2 mm and Curie temperature of 100° C. as a honeycomb basematerial, the honeycomb being a honeycomb base material of PreparationExample 7.

PREPARATION EXAMPLE 8

A honeycomb having a size of 200 mm×100 mm×10 mm, a pitch of 12 mm, anda height of 10 mm was prepared using, as a honeycomb base material, asheet-form PTC heater having Curie temperature of 100° C., which isobtainable by homogeneously supporting a PTC material containing bariumtitanate on an insulating wet-type nonwoven fabric sheet having athickness of 0.2 mm, the honeycomb being a honeycomb base material ofPreparation Example 8.

EXAMPLE 1

A heating heater comprising a panel heater in which a linear heater madeof a surface-insulated nichrome had been held between aluminum plateswas bonded to the circumference of the deodorizing filter of PreparationExample 1 with an ethylene-vinyl acetate copolymer adhesive having aheat resistance to form a thermally regenerative deodorizing filter ofExample 1.

EXAMPLE 2

A heating heater comprising a panel heater in which a linear heater madeof a surface-insulated nichrome had been held between aluminum plateswas bonded to the circumference of the deodorizing filter of PreparationExample 2 with an ethylene-vinyl acetate copolymer adhesive having aheat resistance to form a thermally regenerative deodorizing filter ofExample 2.

EXAMPLE 3

A heating heater comprising a panel heater in which a linear heater madeof nichrome had been held between aluminum plates was bonded to only oneside of the long side parts in the circumference of the deodorizingfilter of Preparation Example 2 with an ethylene-vinyl acetate copolymeradhesive having a heat resistance to form a thermally regenerativedeodorizing filter of Example 3.

EXAMPLE 4

A PTC heater having Curie temperature of 100° C. was bonded to thecircumference of the deodorizing filter of Preparation Example 1 with anethylene-vinyl acetate copolymer adhesive having a heat resistance toform a thermally regenerative deodorizing filter of Example 4.

EXAMPLE 5

A PTC heater having Curie temperature of 100° C. was bonded to thecircumference of the deodorizing filter of Preparation Example 2 with anethylene-vinyl acetate copolymer adhesive having a heat resistance toform a thermally regenerative deodorizing filter of Example 5.

EXAMPLE 6

A particulate high-silica zeolite was included in the honeycomb basematerial of Preparation Example 5 in an amount of 50 g and both openingsof the honeycomb base material were sealed with a stainless steel netinsulated with a heat-resistant resin coating as an gas-permeable basematerial to prepare a deodorizing filter. Then, an aluminum plate fittedwith a terminal for applying a voltage was attached to the liner partsof both sides of the honeycomb base material to form a thermallyregenerative deodorizing filter of Example 6.

EXAMPLE 7

A particulate high-silica zeolite was included in the honeycomb basematerial of Preparation Example 6 in an amount of 50 g and both openingsof the honeycomb base material were sealed with a stainless steel netinsulated with a heat-resistant resin coating as an gas-permeable basematerial to prepare a deodorizing filter. Then, an aluminum plate fittedwith a terminal for applying a voltage was attached to the liner partsof both sides of the honeycomb base material to form a thermallyregenerative deodorizing filter of Example 7.

EXAMPLE 8

A particulate high-silica zeolite was included in the honeycomb basematerial of Preparation Example 7 in an amount of 50 g and both openingsof the honeycomb base material were sealed with an gas-permeableelectroconductive stainless steel net to prepare a deodorizing filter. Aterminal for applying a voltage was attached to the gas-permeablematerials at both sides to form a thermally regenerative deodorizingfilter of Example 8.

EXAMPLE 9

A particulate active carbon was included in the honeycomb base materialof Preparation Example 8 in an amount of 50 g and both openings of thehoneycomb base material were sealed with an gas-permeable aluminum netto prepare a deodorizing filter. A terminal for applying a voltage wasattached to the aluminum nets at both sides to form a thermallyregenerative deodorizing filter of Example 9.

COMPARATIVE EXAMPLE 1

A heating element comprising a panel heater in which a heating heatermade of nichrome had been held between insulated aluminum plates wasbonded to the circumference of the deodorizing filter of PreparationExample 3 with an ethylene-vinyl acetate copolymer adhesive having aheat resistance to form a thermally regenerative deodorizing filter ofComparative Example 1.

COMPARATIVE EXAMPLE 2

A heating heater comprising a panel heater in which a heating elementmade of nichrome had been held between insulated aluminum plates wasbonded to only one side of the long side parts in the circumference ofthe deodorizing filter of Preparation Example 4 with an ethylene-vinylacetate copolymer adhesive having a heat resistance to form a thermallyregenerative deodorizing filter of Comparative Example 2.

COMPARATIVE EXAMPLE 3

A heating element comprising a panel heater in which a heating heatermade of nichrome had been held between insulated aluminum plates wasplaced around the circumference of the deodorizing filter of PreparationExample 1 with a space of 10 mm to form a thermally regenerativedeodorizing filter of Comparative Example 3.

COMPARATIVE EXAMPLE 4

A particulate high-silica zeolite was packed in the cells of thehoneycomb base material of Preparation Example 5 in an amount of 50 g,and one opening of the corrugate was sealed with a urethane foam as angas-permeable material and another opening of the honeycomb basematerial was sealed with a spunbond nonwoven fabric as an gas-permeablebase material to prepare a deodorizing filter, which was used as awater-washing regenerative deodorizing filter of Comparative Example 4.

COMPARATIVE EXAMPLE 5

A particulate high-silica zeolite was packed in the cells of thehoneycomb base material of Preparation Example 5 in an amount of 50 g,and both openings of the honeycomb base material was sealed with aspunbond nonwoven fabric as an gas-permeable base material to prepare adeodorizing filter, which was used as a water-washing regenerativedeodorizing filter of Comparative Example 5.

COMPARATIVE EXAMPLE 6

A particulate high-silica zeolite was packed in the cells of thehoneycomb base material of Preparation Example 7 in an amount of 50 g,and one opening of the honeycomb was sealed with a urethane foam as angas-permeable material and another opening of the honeycomb was sealedwith a spunbond nonwoven fabric as an gas-permeable base material toprepare a deodorizing filter, which was used as a water-washingregenerative deodorizing filter of Comparative Example 6.

COMPARATIVE EXAMPLE 7

A particulate high-silica zeolite was packed in the cells of thehoneycomb base material of Preparation Example 7 in an amount of 50 g,and both openings of the honeycomb was sealed with a spunbond nonwovenfabric as an gas-permeable base material to prepare a deodorizingfilter, which was used as a water-washing regenerative deodorizingfilter of Comparative Example 7.

COMPARATIVE EXAMPLE 8

A particulate active carbon as an adsorbent having electroconductivitywas packed in the cells of the honeycomb base material made of anonwoven fabric having an insulating property in an amount of 50 g andboth openings of the honeycomb base material was sealed with a stainlesssteel net which was gas-permeable and has electroconductivity to form adeodorizing filter of Comparative Example 8 having a structure in whichthe stainless steel net is electrified to thereby cause heat evolutionby PTC.

The following will show evaluation methods and evaluation resultsillustrating superiority of the first embodiment of the invention andwill describe specific advantages of the first embodiment of theinvention.

Acetaldehyde Deodorization Performance Test

Each of the thermally regenerative deodorizing filter of Examples 1 to 3and Comparative Examples 1 to 3 was mounted on an air cleaner for test.While the cleaner was operated in a closed vessel of 1 m³, acetaldehydestandard gas was gradually injected thereinto and the volume W (ml) ofacetaldehyde injected was determined until the acetaldehydeconcentration in the closed vessel detected using a gas detecting tubereached 20 ppm.

Then, each of the thermally regenerative deodorizing filter of Examplesand Comparative Examples was subjected to regeneration treatment by themethod to be mentioned below. Thereafter, the deodorizing test was againcarried out in the same manner as above to determine the volume X (ml)of acetaldehyde injected.

A value (X/W) obtained by dividing the volume of acetaldehyde gasinjected after regeneration by the initial volume of acetaldehyde gasinjected was determined to be defined as a thermal regenerationefficiency (%).

Regeneration Treatment

After the volume W (ml) of acetaldehyde was determined, the heatingheater was switched ON and heating treatment was carried out forminutes. After 15 minutes, the temperature of the heating heater was230° C.

A test was conducted by the above method. The results of evaluating theperformance are shown in Table 1.

TABLE 1 Example or Comparative Thermal regeneration Example efficiency(%) Example 1 106% Example 2 103% Example 3 105% Comparative Example 142% Comparative Example 2 8% Comparative Example 3 12%

From the results shown in Table 1, it is understood that a high thermalregeneration efficiency is obtained since the thermally regenerativedeodorizing filters of at least one embodiment of the invention canefficiently transfer the heat of the heating element brought intocontact with the deodorizing filter.

On the other hand, it is understood that the thermally regenerativedeodorizing filters shown in Comparative Examples cannot efficientlytransfer the heat of the heating element and hardly regenerated sincethey use a nonwoven fabric having a low heat conductivity or the heatingelement does not come into contact with the deodorizing filter.

In particular, a filter using active carbon like the thermallyregenerative deodorizing filter of Comparative Example 2 requires heatof 100° C. or higher for its regeneration and is hardly regenerated at alow temperature, but this disadvantage can be overcome by the use of aheat conductive base material as in the case of the thermallyregenerative deodorizing filter of Example 2.

Furthermore, in the thermally regenerative deodorizing filter of atleast one embodiment of the invention, since the odors entrapped in thedeodorant are completely removed by thermal regeneration, it isunderstood that a higher deodorization efficiency is obtained incomparison with the initial deodorization performance.

This fact means that the deodorizing filter immediately after itspreparation has entrapped a minute amount of organic compounds generatedfrom the binder and the like and odors in the air, and hence is in aslightly deteriorated state in performance.

According to at least one embodiment of the invention, there is obtaineda thermally regenerative deodorizing filter having a large deodorizationcapacity and usable for repeated deodorization by efficientlytransferring the heat of the bonded heating element to the heatconductive deodorizing filter after use.

The following will show evaluation methods and evaluation resultsillustrating superiority of the second embodiment of the invention andwill describe specific advantages of the second embodiment of theinvention.

Acetaldehyde Deodorization Performance Test

Each of the thermally regenerative deodorizing filter of Examples 1, 2,4, and 5 was mounted on an air cleaner for test. While the cleaner wasoperated in a closed vessel of 1 m³, acetaldehyde standard gas wasgradually injected thereinto and the volume W (ml) of acetaldehydeinjected was determined until the acetaldehyde concentration in theclosed vessel detected using a gas detecting tube reached 20 ppm.

Then, each test body was subjected to regeneration treatment by themethod to be mentioned below. Thereafter, the deodorizing test was againcarried out in the same manner as above to determine the volume X (ml)of acetaldehyde injected.

A value (X/W) obtained by dividing the volume of acetaldehyde gasinjected after regeneration by the initial volume of acetaldehyde gasinjected was determined and was defined as a thermal regenerationefficiency (%).

Regeneration Treatment A

After the volume W (ml) of acetaldehyde was determined, the heatingheater was switched ON and heating treatment was carried out forminutes.

Regeneration Treatment B

After the volume W (ml) of acetaldehyde was determined, the heatingheater was switched ON and heating treatment was carried out for 20minutes.

Shape Test

On each test body subjected to thermal regenerative treatment atRegeneration treatment B, shape distortion was evaluated visuallyaccording to the following standard.

Evaluation Level

: No change is observed before test.

◯: Slight distortion is observed.

Δ: Shape distortion and exfoliation at adhered part are observed.

X: Structure cannot be maintained.

A test was conducted by the above method. The results of evaluating theperformance are shown in Table 2.

TABLE 2 Thermal regeneration Thermal efficiency A regeneration Exampleor ($) efficiency B (%) Shape Comparative (Regeneration (Regenerationtest Example treatment A) treatment B) result Example 1 102 78 ◯ Example2 104 73 Δ Example 4 103 104 ⊚ Example 5 101 101 ⊚

From the results shown in Table 2, since the heat of the heating elementbrought into contact with the deodorant filter is efficientlytransferred to the deodorizing filter and contributes to regeneration inthe thermally regenerative deodorizing filters of at least oneembodiment of the invention, a high deodorization efficiency wasobtained in any of Examples 1, 2, 4, and 5 in the case of Regenerationtreatment A.

However, the deodorizing filters of Examples 1 and 2 exhibited a lowvalue in the case of Regeneration treatment B. This result may beexplainable as follows: since the regeneration treatment was carried outfor a long period of 120 minutes, the adhesive part was carbonized intogases and the filter itself adsorbed these combustion gases, whereby thedeodorization efficiency was lowered.

On the other hand, the thermally regenerative deodorizing filters ofExamples 4 and 5 according to the second embodiment maintain a constanttemperature of 100° C. which is Curie temperature thereof, and hencesuch an influence is not observed. This tendency is remarkable from theresults of the shape test. When heated for a long time in a statewithout temperature controlling function like a nichrome linear heater,the temperature increased temperature was transferred to the deodorizingfilter, that the adhesive used for the honeycomb base material and theadhesive used at the attached part between the heater and thedeodorizing filter were carbonized and embrittled to cause exfoliation,falling of the heater, and the like.

In the test bodies of Examples 1 and 2 in which a nichrome linear heaterwas used, the temperature of the heater part after 120 minutes reached ahigh temperature near to 300° C.

Usually, heat of about 100° C. to 150° C. is necessary for completeregeneration of the deodorization performance of the deodorant. However,there is a risk that the surface conditions of the deodorant is modifiedto lower the deodorization performance and the binder or the like usedin combination are thermally decomposed to generate decomposition gaseswhich deteriorates the performance, and the filter itself is burned andcarbonized under an excessively high temperature condition, so that thecondition is not preferred.

As an element to be built in various air-conditioning equipments, thetest bodies such as those of Examples 1 and 2, which is for example anelement such as the nichrome linear heater elevating the temperature toa high temperature and difficult to control are not suitable, also fromthe viewpoint of safe use of a filter.

The use of the thermally regenerative deodorizing filter of the secondembodiment enables repeated use any number of times, and it is possibleto use it safely without risk of combustion and ignition even at heatingover a long period of time.

According to the at least one embodiment of the invention, there isobtained a thermally regenerative deodorizing filter having a largedeodorization capacity and usable safely for repeated deodorization overa long period of time, since the combined PTC heater controlstemperature at a constant temperature after use.

The following will show evaluation methods and evaluation resultsillustrating superiority of the third embodiment of the invention andwill describe specific advantages of the third embodiment of theinvention.

Ammonia Deodorization Performance Test

Each of the thermally regenerative deodorizing filter of Examples 6 and7 and Comparative Examples 4 and 5 was mounted on an air cleaner fortest. While the cleaner was operated in a closed vessel of 1 m³, ammoniastandard gas was gradually injected thereinto and the volume W (ml) ofammonia injected was determined until the ammonia concentration in theclosed vessel detected using an ammonia gas sensor reached 20 ppm.

Then, each of the deodorizing filter of Examples and ComparativeExamples was subjected to regeneration treatment by the method to bementioned below. Thereafter, the deodorization test was again carriedout in the same manner as above to determine the volume X (ml) ofacetaldehyde injected.

A value (X/W) obtained by dividing the volume of ammonia gas injectedafter regeneration by the initial volume of ammonia gas injected wasdetermined and was defined as an ammonia-deodorizing regeneration rate(%).

Acetaldehyde Deodorization Performance Test

Each of the thermally regenerative deodorizing filter of Examples 6 and7 and Comparative Examples 4 and 5 was mounted on an air cleaner fortest. While the cleaner was operated in a closed vessel of 1 m³,acetaldehyde standard gas was gradually injected thereinto and thevolume Y (ml) of acetaldehyde injected was determined until theacetaldehyde concentration in the closed vessel detected using a VOCsensor reached 5 ppm.

Then, each of the deodorizing filters of Examples 6 and 7 andComparative Examples 4 and 5 was subjected to regeneration treatment bythe method to be mentioned below. Thereafter, the deodorizing test wasagain carried out in the same manner as above to determine the volume Z(ml) of acetaldehyde injected.

A value (Z/Y) obtained by dividing the volume of acetaldehyde gasinjected after regeneration by the initial volume of acetaldehyde gasinjected was determined and was defined as an aldehyde-deodorizingregeneration rate (%).

Regeneration Treatment (Thermal Regeneration)

On the test bodies of Examples 6 and 7, after the test was finished inthe ammonia deodorization performance test and in the aldehydedeodorization performance test, a voltage was applied to the terminalsattached to the end of each honeycomb to evolve heat on the PTC sheet,whereby regeneration treatment was carried out under 180 minutesheating.

After the thermal regeneration, the test bodies were allowed to standuntil the temperature thereof became to a room temperature.

Regeneration Treatment (Water-Washing Regeneration)

On the test bodies of Comparative Examples 4 and 5, in the ammoniadeodorization performance test or in the of aldehyde deodorizationperformance test, the deodorizing filters of examples and ComparativeExamples used for the first measurement were individually immersed for 1hour in an aqueous solution in which a standard amount of a commerciallyavailable household neutral detergent (trade name “Mamalemon”,manufactured by Lion Corporation.) was further diluted 10 times, thenthoroughly rinsed by immersion for 1 hour while introducing tap water,and dried in the sun for 8 hours after draining off the water, wherebytreatment for regenerating the deodorizing ability was carried out.

Shape Test

On each test body subjected to thermal regenerative treatment repeated10 times, shape distortion was evaluated visually according to thefollowing standard.

Evaluation Level

: No change is observed before test.

◯: Slight distortion is observed.

Δ: Shape distortion and exfoliation at adhered part are observed.

X: Structure cannot be maintained.

A test was conducted by the above method. The results of evaluating theperformance are shown in Table 3.

TABLE 3 Example or Aldehyde Ammonia Comparative deodorizationdeodorization Shape Example test (%) test (%) test Example 6 101 98 ⊚Example 7 100 97 ⊚ Comparative 56 67 Δ Example 4 Comparative 53 65 ◯Example 5

From the results of Table 3, it is understood that a regenerationefficiency of nearly 100% is obtained for both of aldehyde and ammonia,when the thermally regenerative deodorizing filters of Examples 6 and 7which are practical examples of the third embodiment are used.

On the other hand, when the water-washing regenerative deodorizingfilters of Comparative Examples 4 and 5 are used, it is understood thatthe deodorization performance is regenerated to only about half extentand thus the regeneration rate is low.

The reasons therefor include the following: a sufficient regenerationcannot be achieved when a low-temperature water like tap water is used,it is difficult to remove water thoroughly since an inclusion typedeodorizing filter is poor in air permeability and thus is difficult todry, and the like.

Moreover, from the results of the shape test, it is revealed that thewater-washing regenerative filters of Comparative Examples 4 and 5 aredifficult to maintain the shape thereof.

This is because water at water-washing is a large burden to the supportand the shape distortion and the like 5 are induced.

Thus, the water-washing type deodorizing filter requires atime-consuming washing operation but the regeneration efficiency is low.However, both of the test filter or the like operation, and it ispossible to regenerate the deodorization performance only by applying avoltage.

According to the at least one embodiment of the invention, there isobtained a thermally regenerative deodorizing filter having a largedeodorization capacity and capable of regeneration of the deodorizationperformance of the sealed deodorant and efficient repeated deodorizationany number of times by heating the PTC heater placed at the inner coreor liner part after use.

The following will show evaluation methods and evaluation resultsillustrating superiority of the fourth embodiment of the invention andwill describe specific advantages of the fourth embodiment of theinvention.

Ammonia Deodorization Performance Test

Each of the thermally regenerative deodorizing filter of Examples 8 and9 and Comparative Examples 6 to 8 was mounted on an air cleaner fortest. While the cleaner was operated in a closed vessel of 1 m³, ammoniastandard gas was gradually injected thereinto and the volume W (ml) ofammonia injected was determined until the ammonia concentration in theclosed vessel detected using an ammonia gas sensor reached 20 ppm.

Then, each of the deodorizing filter of Examples and ComparativeExamples was subjected to regeneration treatment by the method to bementioned below. Thereafter, the deodorization test was again carriedout in the same manner as above to determine the volume X (ml) ofammonia injected.

A value (X/W) obtained by dividing the volume of ammonia gas injectedafter regeneration by the initial volume of ammonia gas injected wasdetermined and was defined as an ammonia-deodorizing regeneration rate(s).

Acetaldehyde Deodorization Performance Test

Each of the thermally regenerative deodorizing filter of Examples 8 and9 and Comparative Examples 6 to 8 was mounted on an air cleaner fortest. While the cleaner was operated in a closed vessel of 1 m³,acetaldehyde standard gas was gradually injected thereinto and thevolume Y (ml) of acetaldehyde injected was determined until theacetaldehyde concentration in the closed vessel detected using a VOCsensor reached 5 ppm.

Then, each of the deodorizing filters of Examples 8 and 9 andComparative Examples 6 to 8 was subjected to regeneration treatment bythe method to be mentioned below. Thereafter, the deodorizing test wasagain carried out in the same manner as above to determine the volume Z(ml) of acetaldehyde injected.

A value (Z/Y) obtained by dividing the volume of acetaldehyde gasinjected after regeneration by the initial volume of acetaldehyde gasinjected was determined and was defined as an aldehyde-deodorizingregeneration rate (%).

Regeneration Treatment (Thermal Regeneration by Electrification)

On the test bodies of Examples 8 and 9 and Comparative Example 8, afterthe test was finished in the ammonia deodorization performance test andin the aldehyde deodorization performance test, a voltage was applied tothe terminals attached to the end of each honeycomb to electrify the PTCsheet or the adsorbent, whereby regeneration treatment was carried outfor 180 minutes.

After the thermal regeneration, the test bodies were allowed to standuntil the temperature thereof became to a room temperature.

Regeneration Treatment (Water-Washing Regeneration)

On the test bodies of Comparative Examples 6 and 7, in the ammoniadeodorization performance test or in the aldehyde deodorizationperformance test, the deodorizing filters of examples and ComparativeExamples used for the first measurement were individually immersed for 1hour in an aqueous solution in which a standard amount of a commerciallyavailable household neutral detergent (trade name “Mamalemon”,manufactured by Lion Corporation.) was 10 further diluted 10 times, thenthoroughly rinsed by immersion for 1 hour while introducing tap water,and dried in the sun for 8 hours after draining off the water, wherebytreatment for regenerating the deodorizing ability was carried out.

Shape Test

On each test body subjected to thermal regeneration treatment repeated10 times, shape distortion was evaluated visually according to thefollowing standard.

Evaluation Level

: No change is observed before test.

◯: Slight distortion is observed.

Δ: Shape distortion and exfoliation at adhered part are observed.

X: Structure cannot be maintained.

A test was conducted by the above method. The results of evaluating theperformance are shown in Table 4.

TABLE 4 Example or Aldehyde Ammonia Comparative deodorizationdeodorization Shape Example test (%) test (%) test Example 8 100 98 ⊚Example 9 98 97 ⊚ Comparative 67 62 Δ Example 6 Comparative 58 65 ◯Example 7 Comparative 47 31 ⊚ Example 8

From the results of Table 4, it is understood that a regenerationefficiency of nearly 100% is obtained for both of aldehyde and ammoniawhen the thermally regenerative deodorizing filters of Examples 8 and 9of the 10 fourth embodiment are used.

On the other hand, when the water-washing regenerative deodorizingfilters of Comparative Examples 6, 7 and 8 are used, it is understoodthat the deodorization performance is regenerated to only about halfextent and thus the regeneration rate is low.

The reasons therefor include the following: a sufficient regenerationcannot be achieved when a low-temperature water like tap water is used,it is difficult to remove water thoroughly since an inclusion typedeodorizing filter is poor in air permeability and thus is difficult todry, and the like.

Moreover, from the results of the shape test, it is revealed that thewater-washing regenerative filters of Comparative Examples are difficultto maintain the shape thereof.

This is because water at water-washing is a large burden to the supportand the shape distortion and the like are induced.

Thus, the water-washing type deodorizing filter requires atime-consuming washing operation but the regeneration efficiency is low.However, each of the test bodies of Examples does not require removal ofthe filter or the like operation, and it is possible to regenerate thedeodorization performance only by applying a voltage.

Moreover, in the deodorizing filter of Comparative Example 8, thehoneycomb base material itself has no electroconductivity and thedeodorant is electrified. However, in the case that the deodorant iselectrified, it is difficult to electrify the whole filter evenly sincethe electric current flows through only low resistant paths among pathsshort-circuited with the electroconductive nets at both ends and, inaddition, it is impossible to apply heat necessary for regeneration ofthe deodorization performance, to the filter.

According to the at least one embodiment of the invention, there isobtained a thermally regenerative deodorizing filter having a largedeodorization capacity and capable of regeneration of the deodorizationperformance of the sealed deodorant and efficient repeated deodorizationany number of times by electrifying the PTC heater used as a honeycombbase material after use.

INDUSTRIAL APPLICABILITY

The thermally regenerative deodorizing filter of at least one embodimentof the invention can efficiently regenerate the deodorizationperformance by integrally comprising a deodorizing filter and a heatingelement. In particular, the use of a PTC heater as a heating heater partcan realize a deodorizing filter having high safety and energyefficiency. Thus, the deodorizing filter has an extremely largeindustrial applicability.

1. A thermally regenerative deodorizing filter comprising: a honeycombbase material of a deodorizing filter, which comprises at least a firstkind of electroconductive sheet and a second kind of electroconductivesheet, a deodorant packed in a cell of the honeycomb base material, anda gas-permeable base material sealing openings at the both sides of thehoneycomb base material, wherein at least one of said kinds of saidelectroconductive sheets comprises a PTC heater and at least one of saidkinds of electroconductive sheets does not comprise a PTC heater.
 2. Thethermally regenerative deodorizing filter according to claim 1, whereinthe PTC heater is a ceramic PTC heater.
 3. The thermally regenerativedeodorizing filter according to claim 1, wherein the PTC heater is anorganic PTC heater.
 4. A thermally regenerative deodorizing filter,which comprises a honeycomb base material, a deodorant packed in a cellof the honeycomb base material, and a gas-permeable base material whichseals openings at the both sides of the honeycomb base material, whereinthe honeycomb base material comprises a PTC heater, the gas-permeablebase material comprises an electroconductive material, and the PTCheater is heated by applying a voltage between the gas-permeable basematerial.
 5. The thermally regenerative deodorizing filter according toclaim 4, wherein the PTC heater is a ceramic PTC heater.
 6. Thethermally regenerative deodorizing filter according to claim 4, whereinthe PTC heater is an organic PTC heater.
 7. The thermally regenerativedeodorizing filter according to claim 1 wherein: at least one of theelectroconductive sheets is a corrugated inner core part, and at leastone of the electroconductive sheets is a liner part coupled to the atleast one corrugated inner core part.
 8. The thermally regenerativedeodorizing filter according to claim 1 wherein the PTC heater is aself-temperature controlling type at an electrification.
 9. Thethermally regenerative deodorizing filter according to claim 4 whereinthe PTC heater is a self-temperature controlling type at anelectrification.